Insects on Morning Glories

True to their name, morning glory plants (Ipomoea spp.), produce lovely, trumpet-shaped flowers that unfurl early in the day. The genus includes both annual and tender perennial vines. The common, purple-flowered morning glory (Ipomoea purpurea), is an annual, while the white-flowered moonflower (Ipomoea alba) grows as a perennial in U.S. Department of Agriculture plant hardiness zones 10 through 12 and as an annual elsewhere. Morning glories can be fast, aggressive growers, and some species are considered invasive. The plants can be vulnerable to attack from several insect pests.

Aphids

Aphids are soft-bodied, pear-shaped insects less than 1/16 inch long. Aphids insert sharp mouth parts into the plant to suck out the phloem. Heavy infestations can cause distorted or stunted growth and leaf stippling. Aphids tend to feed in colonies and excrete honeydew, a sticky sweet substance that can attract ants to the morning glory. Honeydew also provides a breeding ground for sooty mold. Both honeydew deposits and sooty mold can interfere with the morning glory's photosynthesis. A hard spray from the garden hose knocks aphids off the morning glory. Repeat every two or three days until the pests are gone or populations are reduced enough for beneficial insects to finish them off. A heavy infestation may require spraying the plant with a soap solution. Mix 1 tablespoon of a mild dish detergent with 1 quart of water and spray the plant thoroughly, paying attention to the undersides of the leaves. Once the spray dries completely, rinse it off with plain water. Repeat every seven to 10 days.

Caterpillars

The larvae of various species of moths and butterflies, caterpillars in large numbers can decimate morning glory plants. Most feed on morning glory leaves, resulting in unsightly holes or ragged tears in the leaves, or they can strip the plant of its leaves. Some bore into tender stems, causing the plants to collapse or wilt. Pick off larger caterpillars and worms by hand and drop them into a bucket of soapy water to kill them. Heavily infested plants may be treated with Bacillus thuringiensis, a poison caterpillars eat. Bt can be dusted on morning glory foliage as soon as you see caterpillars. Dust again every seven to 10 days, as needed. Make sure the dust thoroughly coats the foliage so the caterpillars will eat it. Bt can also be mixed with water and sprayed on the plants. Add 1/2 teaspoon to 1 gallon of water and spray the morning glory thoroughly. Read the instructions on the label because rates and methods may vary.

Ants

Ants don't feed on morning glory plants, but may march up and down the stems and around the foliage in large numbers, searching for honeydew to eat. Ants protect aphids by driving away predatory insects. Controlling the ant population clears the way for beneficial insects to deal with aphid infestations. Readily available ant baits or stakes provide poisoned food for the ants to take back to their colonies for other ants to eat. The process is somewhat slow, but the entire colony will eventually die. Bait stations or stakes should be placed near the morning glory or close to the paths ants use to travel to and from the plant, but not where children or pets can get to them.

Chemical Controls

Insecticidal soaps are readily available to control aphids and other insects, and have less impact on the environment. These multipurpose pesticides, containing elemental sulfur and potassium salts of fatty acids, are usually available in both ready-to-use and concentrated form. Thoroughly spray morning glory plants with ready-to-use formulas to achieve full coverage, making sure the insects come into contact with the poison. Repeat weekly, as needed, for up to three applications. Always check the label's directions and follow them carefully.

About the Author

Audrey Lynn has been a journalist and writer since 1974. She edited a weekly home-and-garden tabloid for her hometown newspaper and has regularly contributed to weekly and daily newspapers, as well as "Law and Order" magazine. A Hambidge Fellow, Lynn studied English at Columbus State University.